Known powered roller conveyors used for conveying large flat objects, such as luggage trays utilized at airports, have conventionally utilized a plurality of belt-driven rollers. These conveyors, however, have necessarily required substantial guide structure in order to properly confine the moving trays, which guide structure becomes particularly complex when the conveyor involves curved sections.
In an attempt to improve upon such tray conveyors, it has been proposed (see U.S. Pat. Nos. 3,753,485 and 3,826,351) to utilize flanged rollers which provide not only the support and driving engagement with the trays, but also function as guide or alignment members for confining the trays during their movement along the conveyor. While the conveyors of these latter-mentioned patents provide for more positive control over the trays due to the manner in which the flanged rollers confine the tray therebetween, nevertheless the conveyors of these patents possess many of the same deficiencies possessed by the other known pan coveyors in that they utilize an extremely complex drive arrangement involving a plurality of belts, particularly twisted belts, for driving the individual roller shafts. This type of driving arrangement is undesirably complex and, under some conditions, requires an undesirable amount of maintenance and repair.
Accordingly, it is an object of the present invention to provide an improved powered pan conveyor which overcomes the above-mentioned disadvantages and, in particular, utilizes an improved simplified drive mechanism so as to result in a more compact and economical structure, and which drive mechanism results in substantially improved conveyor performance while requiring substantially less maintenance and repair.
It is also an object of the invention to provide an improved pan conveyor, as aforesaid, which utilizes a pair of flanged rollers for simplifying both the driving of the conveyor and the positive guiding of the conveyed objects. At least one roller of each pair is positively frictionally driven by and comprises a part of the improved drive mechanism, with the roller being directly frictionally driven from a rotatable line shaft which extends longitudinally of the conveyor, whereby the flanged rollers are positively controlled and driven in a simplified manner.
A further object of the invention is to provide an improved pan conveyor, as aforesaid, which incorporates the improved drive mechanism, with the latter being highly suitable for use not only in straight conveyor sections but also in curved conveyor sections. This improved drive mechanism is also highly desirable for conveyors having a plurality of individually controlled zones of rollers spaced longitudinally thereof for permitting accumulation of articles on the conveyor.
In the following discussion, while reference is made to a "pan" or "tray", it will be appreciated that the conveyor of this invention is highly desirable for use on many different types of articles having a relatively large flat bottom surface, particularly pallets and the like, and reference to "tray" or "pan" will encompass such other articles.
Other objects and purposes of the invention will be apparent to persons familiar with conveyors of this general type upon reading the following specification and inspecting the accompanying drawings.